Absorbent articles, classified as sanitary napkins, catamenial pads or feminine pads, are designed to be worn by a female to absorb menstrual fluids and other excrements discharged by the body during a menstrual period. Sanitary napkins are external devices which are generally held in position by an adhesive or by a mechanical attachment to an undergarment. Such products differ from tampons which are classified as internal devices and which are designed to be physically inserted into the vagina. Functionally, sanitary napkins are different from other external devices, such as pantiliners or panty shields, in that they are generally constructed to absorb a greater quantity of body fluid and are designed to be worn for a longer period of time; for example, overnight if needed.
In order to adequately perform their function, modern sanitary napkins are constructed of highly absorbent materials. However, if any absorbent material is utilized to, or near, the point where it becomes fully saturated, there is a possibility that leakage of body fluid could occur which might stain the user's clothing.
It is, therefore, desirable to construct an absorbent article which could be visually examined to determine if it is near its fluid-saturation point. Quite often, the absorption of body fluids is into a target zone on the top of the product; and it is not clear, from looking at the top of the product, if the product is close to being saturated. It is also difficult to tell when the target area is so close to being fully saturated that leakage may soon occur.
Therefore, there is a need to provide an absorbent article which can provide the user with a quick visual inspection to determine if it is near its absorption limits. If the product is close to its limit, the user could then replace it before leakage occurs.
There are several U.S. patents which teach the advantages of using an absorbent material which has good fluid-wicking properties for at least a portion of the absorbent layer.
U.S. Pat. No. 4,732,312 issued to Fender et al. teaches an absorbent pad containing a nonwoven hydrophilic thermoplastic filamentary microfiberous web as part of the absorbent material. The microfiberous web exhibits good wicking and fluid-retention properties. The microfiberous web is not used to provide an indication that the pad is close to absorbent capacity.
A second patent, U.S. Pat. No. 3,525,338 issued to Bernardin, discloses utilizing a layer of glass microfibers as part of the absorbent material. The glass microfiberous layer has good absorbent capacity and wicking capabilities. When a layer of glass microfibers is deposited horizontally between two layers of conventional absorbent material, the absorbent capacity of the sanitary napkin is increased as well as its efficiency. The latter is due to the lateral wicking properties of the layer of glass microfibers. The use of absorbent materials, having varying transverse wicking rates which can serve as a visual indicator, is not taught in this patent. Furthermore, neither Fender nor Bernardin teach using layers with various wicking rates as a method of providing an indication of the saturation level of an absorbent article.
There is also a need to design an absorbent article, where the crotch portion of the user's undergarment, to which the absorbent article is attached, will not fold onto the body-facing side of the product. This will assist in preventing the undergarment from becoming stained by body fluid. One method of overcoming this problem is to design absorbent articles with flaps or wings which extend outward from the central absorbent. However, the addition of flaps or wings makes the product more expensive. Typically, sanitary napkins having flaps or wings use a central adhesive strip which attaches the product to the crotch portion of a user's undergarment. The side flaps or wings are teen folded around the outer surface of the undergarment to protect the undergarment from becoming stained. Some U.S. patents which teach the use of flaps or wings include the following.
U.S. Pat. No. 2,787,271 issued to Clark describes a sanitary napkin comprising a rectangular central pad having a pair of lateral flaps integrally formed with the pad. The flaps are adapted to fold downward and bear against the inner surface of the wearer's thighs. The flaps or wings are designed to stop any overflow of body fluid from staining the user's clothing. The central pad has an absorbent core body which extends without interruption into the lateral flaps.
U.S. Pat. No. 3,397,697 issued to Rickard describes a disposable sanitary shield for undergarments. This shield comprises an elongated sheet of flexible material divided into at least two panels which are joined by an intermediate neck-like portion. Portions of the panels, located adjacent to the neck-like portion, include wing-like flaps which are adapted to be folded over each other. This enables the flaps to encircle the crotch portion of the undergarment and prevent staining.
U.S. Pat. No. 4,285,343 issued to McNair describes a sanitary napkin having a central absorbent pad with laterally extending side panels. The side panels can be formed either integrally with the central absorbent or be formed separately and then secured to the longitudinal edges of the central absorbent.
U.S. Pat. No. 4,687,478 issued to Van Tilburg describes a sanitary napkin having two flaps that extend outward from an absorbent means. The absorbent means is secured in the crotch of a panty, and the flaps are secured about the elastic edges of a panty by an adhesive.
Despite the teachings of the prior art, there is still a need for an absorbent article which can be visually inspected to determine if it is at, or near, its fluid-saturation limit.